Apropos of nothing, on a recent LHR-LIS flight my BP pinged at the gate because I had been moved from (self-selected) 2A to 1A and it turned out this was because I was, seemingly, the sole Business passenger on a flight packed to the brim with Economy flyers (possibly due to a cancellation or TAP's recent labour dispute issues).

Never before had the curtain right behind my head when seated in Row 1, and getting served the sole Business meal (the passengers in 1D & 1F didn't seem to be on Business tickets and there was nobody in 1C) felt weird and oddly disconcerting

TAP could alternatively have bumped a couple of people up to Biz in this situation to maintain a more normal Biz/Econ cabin split but didn't so it seems like the OP was lucky